1. Field of the Invention
The present invention relates to plumbing vent stacks that extend above the roof on a building for venting of sewer gases. In particular, the present invention relates to a vent pipe protective cover for protecting the vent pipe when installed over the vent stack.
2. Description of Related Art
A vent stack protrudes from the roof deck of a building with toilet facilities to vent and remove the sewer gases from the sewer trap. The vent stack is normally installed at the time the building is built, integrated into the roof as it is installed and sealed with a flashing that creates a gasket seal against the vent pipe. The installed vent stack system is normally weatherproofed at that time. Studies have shown that in as little as 6 or 7 years, the flashing can deteriorate where it contacts the pipe and begin to leak due to the exposure to the elements. In addition, animals such as mammals, birds, reptiles, and the like may damage the flashing integrity while nesting, feeding, or the like.
In states where there is a raised crown surrounding the base used for the flashing around the vent stack pipe, it is quite common that the flashing leaks begin at the intersection where the vent pipe enters the crown.
When the flashing begins to leak, the building owner is faced with either replacing the entire vent which is an expensive and probably prohibitive procedure, or use one of a number of covers. A number of covers have been available for covering the leaking roof vent stack, however, the current ones all suffer from problems such as the need to have multiple sizes, ones to accommodate different roof pitches and attachment means which are readily susceptible to leaking. Because vent stacks are not cut to exact standard sizes, they vary in height by a large amount and covers of a specific height are difficult to install, if not impossible in some cases to use. In the case where there is a raised crown surrounding the base, many of the solutions will not work at all since they are designed to be used with a flat base, and will not work with a raised base.
U.S. Pat. No. 3,797,181 issued Mar. 19, 1974 to Nievelt, teaches a cylindrical cover of a fixed size, which requires a different height device for each vent pipe. In U.S. Pat. No. 5,245,804 issued Sep. 21, 1993 to Schieddegger et al., a roof vent pipe shield comprises an outer plastic cylinder and an inner plastic cylinder connected at one end by a fusion creating space between the cylinders. Once again, the device requires that it be custom made to a height that matches each vent pipe.
U.S. Pat. No. 5,694,724 issued Dec. 9, 1997 to Santiago discloses a stack vent cover used for flashing. This cover acts as flashing and requires attachment to the roof. In U.S. Pat. No. 6,244,006 issued Jun. 12, 2001 to Shue et al., there is taught a vent pipe cover with a flat flashing porting and an end cap. The end cap does not appear to be secured and is sufficiently small that it can be blown off the device in high winds.